Antiperspirant compositions are well known in the cosmetic art. An ideal antiperspirant composition is stable for the life of the composition, effectively delivers the antiperspirant compound to the skin, does not leave a visually observable white residue on the skin or clothing, and is esthetically pleasing to the consumer.
Antiperspirant compositions are available in a variety of forms, such as aerosol suspensions; pump sprays; roll-on powders; emulsions, lotions, or suspensions; and solid gels, waxes, creams, or suspensions. Antiperspirant compositions traditionally have been prepared as either oil-in-water emulsions or water-in-oil emulsions. Therefore, antiperspirant compositions of any form typically have a milky or opaque appearance, but some antiperspirant compositions are transparent. Antiperspirant compositions conventionally are manufactured by complex methods. Antiperspirant compositions prepared as emulsions often feel wet or oily when applied to the skin, and often remain tacky after the carrier of the composition evaporates. In addition, many emulsion-type antiperspirant compositions leave a white, staining residue on contacted skin or clothing.
Roll-on and gelled emulsion-type antiperspirant compositions are used by rubbing an area of the body, such as the underarm, to apply a layer of the composition to the skin, and thereby reduce odor and/or perspiration. Roll-on and gel antiperspirant compositions preferably possess the esthetic properties of smoothness, nonoiliness and nontackiness. Gelled antiperspirant compositions also require a sufficient firmness to maintain its shape. Another highly desirable, but hard to achieve, esthetic property is avoiding a visible residue, e.g., a white layer, that is left on the skin or clothing after the antiperspirant composition is applied.
Nonemulsified antiperspirant compositions also are known in the art. However, nonemulsified compositions often require shaking prior to each use in order to redisperse the insoluble antiperspirant compound that has separated from the composition. Nonemulsified antiperspirant compositions that do not require shaking prior to each use, such as an antiperspirant creme or paste, typically include a relatively high percentage of suspending agents, like an organoclay. The presence of an organoclay in an antiperspirant composition is a principal source of the whitening and staining of skin and clothing.
Investigators have searched for antiperspirant compositions that display the above-listed desirable properties. A roll-on antiperspirant is difficult to formulate and manufacture because the composition requires a sufficient viscosity to adhere to the skin, resists dripping off or running down the skin, and yet is not tacky or sticky. A gel antiperspirant composition is difficult to formulate and manufacture because the composition requires sufficient firmness to withstand rubbing across the skin to deliver a sufficient amount of the antiperspirant compound to the skin. Additional formulation parameters include viscosity control, lack of syneresis, and nontackiness.
A gel antiperspirant composition which has esthetic and functional properties equal to or better than presently available antiperspirant compositions is highly desired by consumers. However, providing a commercially acceptable gel antiperspirant composition requires overcoming several formulation and manufacturing problems.
Gelled antiperspirant compositions incorporate a gelling agent to build up the solid structure, or firmness, of the composition. Solid antiperspirant compositions typically are based on solid fatty alcohols containing 14 to 20 carbon atoms as the solidifying agent. In addition, nonvolatile emollients are included in the composition to minimize tackiness and improve sensory properties, thereby improving ease of application, esthetics, and consumer appeal.
Solid antiperspirant compositions are divided into three main classes, i.e., compressed powder sticks, gel sticks and wax sticks. Each of these classes has advantages, but each class also has particular disadvantages. Compressed powder sticks for example are frequently brittle and hard, and leave a cosmetically unacceptable powdery residue after application. Frequently, wax-based products are cosmetically unacceptable because of such factors as hardness, greasiness and tackiness. The visually observable white residue remaining after application also is esthetically undesirable.
Gel-type solid antiperspirant compositions have several advantages over both compressed powder sticks and wax sticks. For example, the gel antiperspirant compositions leave less residue or dust on the skin. The gel antiperspirant compositions also glide easily over the skin surface resulting in an easy and comfortable application of the composition.
However, the preparation of antiperspirant compositions in the form of an effective and stable gel is difficult. For example, a critical ingredient in gel antiperspirant compositions is the gelling agent. Many prior gel antiperspirant compositions contain gelled hydroalcoholic solutions including a gelling agent, such as sodium stearate, to form the gel. However, common gelling agents cannot be used in the presence of acidic antiperspirant compounds because of an interaction between the gelling agent, which is alkaline, and the antiperspirant compound.
Prior gel antiperspirant compositions also typically were divided into three main classes. One of these classes is the optically clear gelled emulsion compositions. These compositions include a water phase and an oil phase. The oil phase is suspended in the water phase by using a sufficient amount of an appropriate emulsifier or emulsifiers. The emulsions conventionally contained waxes, silicones, clays and emollients. The optically clear gelled emulsion compositions are illustrated in U.S. Pat. Nos. 4,673,570, 4,268,499, 4,278,655, and 4,350,605; EP 0 450 597; and in "Deodorant and Antiperspirant Formulary," Cosmetics & Toiletries, Dec. 12, 1985, vol. 100, p. 65-75.
The optically clear gelled emulsion compositions often exhibit the disadvantages of composition instability during storage; the development of a hazy or milky appearance during storage; a stringy, tacky, oily consistency and other undesirable esthetics. In additions, the emulsion gel compositions often leave a visible residue, in the form of a white layer, on the skin or clothing. Another disadvantage of optically clear gelled emulsion compositions is the complex method of preparing an optically clear gelled emulsion composition. The method traditionally requires high shear rates during mixing, high processing temperatures, and a series of cooling and heating process steps.
A second class of gel antiperspirant compositions is antiperspirant compositions thickened with 1,3:2,4-dibenzylidene-sorbitol (DBS) or DBS derivatives. Such transparent antiperspirant compositions are disclosed in U.S. Pat. Nos. 4,822,602 and 4,725,430; European Patent Publication 0 512 770; WO91/15191; and WO 92/19222.
Gelled antiperspirant compositions thickened with DBS or DBS-type compounds have a major disadvantage in that the compositions are unstable in the presence of highly acidic antiperspirant compounds at elevated temperatures. In addition, other disadvantages are the high temperature required for manufacturing DBS-thickened compositions (i.e., about 230.degree. F. to about 240.degree. F.), and leaving a visible white residue on the skin and clothing after application.
The third class of gel antiperspirant compositions is the acid-base complex gels. These antiperspirant compositions are prepared by interacting the active antiperspirant compound with a carboxylic acid salt. Acid-based complex gels are disclosed, for example, in U.S. Pat. Nos. 3,255,082 and 2,876,163; and in European Publication No. 0 448 278.
This third class of antiperspirant compositions has a major disadvantage in that the active antiperspirant compound is partially deactivated by the salt, thereby reducing the efficacy of the antiperspirant compound and, accordingly, the antiperspirant composition. In addition, the resulting gels are very brittle, tacky, and/or possess other undesirable esthetic properties, such as in the compositions disclosed in U.S. Pat. No. 3,255,082, which are emulsions or sols.
The problems associated with gel antiperspirants can be partially overcome by formulating a roll-on antiperspirant. Roll-on antiperspirants typically are viscous liquids to semi-solids. However, roll-on antiperspirants often impart a tacky feel and still have the ability to leave an unsightly white residue on the skin. Similarly, aerosol antiperspirants leave a greasy or tacky feeling, or a white residue, on the skin after application.
Investigators have continually sought to provide gel antiperspirant compositions having both long-term stability and sufficient esthetic and functional properties for consumer acceptance. These esthetic and functional properties include a sufficient firmness for application to the skin, no visually observable whitening of the skin and clothing, and the ability to effectively deliver the antiperspirant compound to the skin without providing a tacky or sticky feeling. The present invention is directed to providing gel antiperspirant compositions exhibiting these consumer-acceptable esthetic and functional properties wherein the composition utilizes a nonaqueous carrier and a gelling agent selected from a sterol and a starch hydrolyzate ester of a C.sub.8 to C.sub.22 carboxylic acid. Surprisingly, the compositions can be admixed with a hydrocarbon propellant to provide an aerosol antiperspirant.
Gelled, nonaqueous liquids are known. For example, nonaqueous liquids gelled by the addition of dextrin fatty acid esters are disclosed in Japanese Patent Publications 3,006,283; 1,203,379; 64-207223, 62-121764, 62-143970, and 62-143971. The use of a cellulose fatty acid ester to gel a nonaqueous liquid was disclosed in Japanese Patent Publication 63-360955. A gelling agent for nonaqueous solvent using a combination of a dextrin fatty acid ester and an n-acylaminoacid was disclosed in Japanese Patent Publication 64-207223.
Saito et al. U.S. Pat. No. 3,989,087 and WO93/23008 disclose gelling a nonaqueous system containing aluminum salts using a combination of an n-acylamino-acid amide and 12-hydroxystearic acid. However, high processing temperatures were required to achieve gelling, the product was hard to wash off the skin, and the product lacked consumer-acceptable efficacy. Similar products incorporating polyoxyethylene ether compounds and having improved wash-off properties are disclosed in WO 94/24997. However, the processing temperature required to manufacture the composition offset the improved efficacy.
EP 0,440,387 discloses gelling a C.sub.1 to C.sub.4 alcohol-based antiperspirant composition with a combination of a hydrophobically-treated clay and sucrose esters of tallow fatty acids. However, the stability of these compositions is low and must be improved to provide a consumer-acceptable antiperspirant composition.
Other patents directed either to gelling agents for nonaqueous compositions or to antiperspirant compositions include UK Patent Application GB 2,253,347, which discloses antiperspirant compositions gelled by a compound having polycyclic aromatic and steroidal groups linked by an ester linkage; Tanner U.S. Pat. No. 5,019,375; Orr U.S. Pat. Nos. 4,853,214 and 5,069,897; European Patent Application Publication No. 0 545 002; and WO 93/08840. Mori et al. U.S. Pat. No. 5,013,715 discloses the use of a fatty acid ester of saccharose to gel a nonaqueous liquid. Mori et al. U.S. Pat. No. 4,780,145 discloses the use of a dextrin fatty acid ester to gel nonaqueous liquids. Berndt U.S. Pat. No. 5,338,535 discloses a talc-free body powder including a starch powder and a volatile silicone.